Nonadiabatic effects are ubiquitous in nature and play essential role in many chemically-interesting processes, such as charge and energy transfer and chemical transformations. Nonadiabatic molecular dynamics (NA-MD) is a popular approach for studying coupled nonadiabatic electron-nuclear evolution, and has been successfully applied to study many photovoltaic and photocatalytic materials, as well as biologically-relevant systems. However, the methodology becomes increasingly expensive as the system’s size increases. I will describe our tight-binding fragment-based NA-MD approach for modeling charge and energy transfer in large-scale systems. The approach combines quantum-classical approximation for electron-nuclear dynamics and chemically-motivated fragmentation of the overall system into arbitrary fragments. Several types of fragment molecular orbitals (FMO) will be considered: quasidiabatic, adiabatic, and Löwdin-transformed ones. The dynamics obtained in these representations will be analyzed and compared. The scaling properties will be discussed. The applicability of the approach will be demonstrated on a study of charge transfer in subphtalocyanine(SubPc)/C60 heterojunction. The computational results emphasize the importance of decoherence and details of interfacial structure for obtaining accurate charge transfer timescales in SubPc/C60 herejunctions.

Nonadiabatic molecular dynamics with tight-binding fragment molecular orbitals

253rd National Meeting (2017)

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